Etiology
The causes of male infertility can be classified according to fertility as absolute infertility (azoospermia) and relative infertility (low sperm count or low sperm vitality, etc.), primary infertility and secondary infertility according to clinical manifestations, and pre-testicular, testicular and post-testicular lesions according to the site of sexual organ disease. The causes of male infertility are complex, and the main causes are described below:
(a) Semen abnormalities
1, no sperm or too little sperm
When the sperm density in semen is lower than 0.2 billion/ml, the woman’s chance of conception is reduced, and when it is lower than 0.2 billion/ml (currently considered lower than 0.15 billion/ml), it causes infertility. This infertility can be divided into permanent and temporary, the former is seen in congenital testicular development disorders or testes, seminal vesicles serious lesions; the latter is mostly seen in sexual life too often resulting in sperm production function once failure, generally for sperm reduction rather than total absence of sperm.
2.Poor sperm quality
Poor sperm quality can often cause infertility when there are too many inactive or dead sperm in the semen (more than 20%), or poor sperm motility or abnormal sperm exceeding 30% (currently more than 96%).
3. Abnormal physical and chemical properties of semen
Normal semen condenses into jelly soon after ejaculation and liquefies in the next 15-30 minutes. If the semen does not solidify after ejaculation, or if the liquefaction is incomplete, it often indicates lesions in the seminal vesicles or prostate. Bacterial and viral infections of the genital tract can also cause changes in the composition of semen, resulting in infertility. Infertility can be caused by pathogenic bacteria greater than 103/ml and non-pathogenic bacteria greater than 104/ml in semen.
(B) Sperm production disorders
1, testicular disease itself
Such as testicular tumor, testicular tuberculosis, testicular syphilis, testicular non-specific inflammation, testicular atrophy after trauma or torsion of the spermatic cord, testicular agenesis, etc., can cause spermatogenic dysfunction and infertility.
2.Chromosomal abnormalities
Sex chromosome abnormalities can cause poor differentiation of testes and other sex organs, resulting in true hermaphroditism and congenital testicular hypoplasia. Autosomal abnormalities can lead to metabolic disorders of gonads and spermatogenic cells.
3.Spermatogenesis dysfunction
Long-term consumption of cottonseed oil can affect spermatozoa and cause spermatozoa autoimmunity, which can also cause spermatozoa dysfunction.
4.Local lesions
Diseases such as occult varicocele and giant sphincter effusion affect the local external environment of the testes or cause infertility due to temperature and compression.
(C) Sperm and egg union disorders
1.Sperm duct obstruction
Such as congenital deformities of the vas deferens such as atresia, surgical ligation of the vas deferens, chronic inflammation of the seminal tract and its surrounding tissues, etc.
2, retrograde ejaculation
If the bladder neck has been operated or damaged or scar contracture after surgery to make the urethra deformed, after bilateral lumbar sympathectomy or rectal cancer abdominal perineal surgery, diabetes-induced pubic nerve damage, spermatic cyst hypertrophy, and severe urethral stricture, certain drugs, such as adrenaline blockers, can cause changes in the sympathetic nerve function that innervates the bladder.
3.External genital abnormalities
Such as congenital lack of penis, such as penis is too small, male pseudohermaphroditism, urethral cleft or hypospadias, acquired penile inflammation or injury, scrotal edema, giant testicular sphincter effusion, etc.
4.Male sexual dysfunction
Impotence, premature ejaculation, non-ejaculation, etc.
(iv) Systemic factors
1.Mental and environmental factors
Sudden change of living environment leads to long-term mental tension, high altitude, high temperature, super-intense labor and radiation work.
2, nutritional factors
Severe malnutrition, vitamin A, vitamin E deficiency, trace elements such as zinc, manganese deficiency, calcium, phosphorus metabolism disorders, mercury, arsenic, lead, ethanol, nicotine, cottonseed oil and other toxic substances chronic poisoning, chemotherapy drug treatment, etc.
3.Endocrine diseases
Such as pituitary dwarfism, obesity, reproductive incompetence syndrome, hypopituitarism, congenital gonadal dysplasia, congenital inability to produce sperm syndrome, hyperprolactinism, pituitary tumor or intracranial infection, birth injury, etc.
Examination
Semen analysis
It is an important and easy way to measure male fertility. The normal values of semen routine in China are: semen volume 2-6ml/time (currently considered 1-6ml/time), liquefaction time <30 minutes (<60 minutes), ph value 7.2-8.0, normal value of sperm density >20×106/ml, sperm motility ≥60%, viability grade a >25%, or viability (a+b) > 50%, and sperm malformation <40% (currently considered >96%). The specimens were collected by masturbation or sperm extractor, using special glass vials, without plastic cups or condoms, and the specimens should not be sent for examination for more than 1 hour, with the temperature maintained at 25-35°C and the abstinence time of 3-5 days (2-7 days). Since sperm count and sperm quality often change, the average value should be taken for three consecutive examinations.
Urine and prostate fluid examination
Increased leukocytes in the urine can indicate infection or prostatitis. Retrograde ejaculation can be considered when a large number of sperm are found on urinalysis after ejaculation. Microscopic examination of prostatic fluid with leukocytes >10/HP should be done for bacterial culture of prostatic fluid.
Reproductive endocrine hormone measurement
Including testosterone, testosterone T, LH, FSH and other reproductive endocrine hormones. Combined with semen analysis and physical examination, it can provide identification of the cause of infertility. If T, LH and FSH are all low, secondary hypogonadism can be diagnosed; a simple decrease in T, normal or high LH and an increase in FSH can be diagnosed as primary gonadal failure; a normal T and LH and an elevated FSH can be diagnosed as selective spermatogenic epithelial insufficiency; an increase in T, LH and FSH can be diagnosed as androgen tolerance syndrome.
Anti-sperm antibody test
Immune infertility accounts for 2.7% to 4% of male infertility, and WHO recommends a mixed antiglobulin reaction test (MAR method) and an immunostrain test. Not only can they measure the presence of anti-sperm antibodies in the serum and secretions of infertile couples, but they can also measure whether these antibodies can bind to sperm and distinguish which antibody binds to which region of the sperm. The percentage of microemulsion droplets and active sperm bound in the antiglobulin mixed reaction test should be less than 10%. In the immunostrain test, microemulsion droplets coated with IgA or IgG antibodies on the surface are mixed and incubated with sample sperm, and the antibodies bind to IgA or IgG on the surface of the sperm. The key to the success of this test is that the sperm should be motile. These antibody test results should be interpreted with great care, as some patients have antibodies that do not affect their fertility.